Method and apparatus for stereoscopic photography



Aug. 28, 195.1 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 1 m b v kg g Aug. 28, 1951 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 -14 Sheets-Sheet 2 Aug. 28, 1951 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 SheetsSheet 5 Aug. 28, 1951 A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 4 Aug. 28, 1951 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHQTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 5 H. A. BAcKus Aug. 28, 1951 METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 6 Aug. 28, 1951 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July l, 1947 14 Sheets-Shed 7 2 g I 'A// Aug. 28, 1951 HA. BACKUS' METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY 14 Sheets-Sheet 8 Filed July 1, 1947 0 m2; rmbLbIm METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 H. A, BAcKus' Aug. 28, 1951 14 Sheets-Sheet 9 H. A. B-ACKUS Aug. 28, 1951 METHOD AND APPARATUS FOR STEPEOSCOPIC PHOTOGRAPHY I Filed July 1, 1947 l4 Sheets-Sheet 10 Aug. 28, 1951 H. A. BACKUS 2,566,110

METHOD AND APPARATUS FOR STEREQSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 11 Aug. 28, 1951 2,566,110

METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 a. A. BACKUS 14 Sheets-Sheet 12 Mow;

H. A. BACKUS Aug. 28, 1951 7 METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 13 METHOD AND APPARATUS FOR STEREOSCOPIC PHOTOGRAPHY Filed July 1, 1947 14 Sheets-Sheet 14 PMTFORM 5M MRQQM Patented Aug. 28, 1951 UNITED STATES: eAIENr QFFEE This invention relatesto a method and means" for producing stereoscopic pictures ofthet pe which exhibit binocular stereoscopic relief when viewed through a suitable viewing means.

Pictures of the type to which the invention relates are well known in theory in the prior art and have there been described'as a composite image containing parallel panel views of an object field as seen from a plurality of points of view. Moreover, such an image is acomposite" image composed of a plurality of'suchpanels, different panels containingdifferent portions of the object field on which the camera is focussed, and a single portion of said object-field occurring in a plurality of .panels.

It isof course known that such pictures can be produced by disposing atransparent lenticular element between the lens of the cameraand the sensitized surface or emulsion, which lenticular element, for example, may have one surface formed with a series of parallel, vertical, convex. When relative lateral movement is then ribs. effected between the camera elements and the object being photographed, the lenticular causes a composite image of the type referred toto-be formed on the sensitized surface. When such an image, either negative or positive, is viewed through a properly matched transparent lenticular, some illusion of depth or stereoscopic relief;

is produced.

While in theory such methods have been sound, the results producedin commercial prac+ tice have, up to the present time, been most discouraging, and while many have devoted their time and energies to the production of such pictures for a great number of years, nopractical.

commercial results have been obtained.

As early as the patent to Kanol No. 1,260,682,

it was realized by some that the depth effect could be enhanced in methods of this general type by effecting a relativelateral movement between the sensitized surface and the lenticular during the time the sensitized surface is exposed to the object. The present invention has for its.

principal object the production of pictures having a greatly enhanced. depth effect by a. method. which consists broadly. in effecting a plurality of relative movements of ,anumber ofelements; in. addition to the object being photographed, whichi modify the light passing to :the sensitized surfaceduring the taking of the picture.

In accordance with the present invention it has now been found that the depth effect can also be:

greatly enhanced inpcertain. instances; not only by .effectingthe. relative.,movements to which. i

reference haslbeen made, but byalso varying the speed of ;,such,,re1ative movements or certain. of them during the time-theyareoccurring. It is.v

an important object ofthe invent ion to provide a method and means for effecting such speed:

h n e Itis a furtherobject of the invention .to provide a method and means for correlating the. various relative. movements which have been entioned. Still further, in accordancewith one of the features oftheinvention these movements or certain ofthem-are correlated with an 'adjustable lensaperture so as to vary theapertu're,

opening during such-movementsso as to control the photographic density-and to increase the depth effect even to a. greater. extent.

. In accordance withanother feature'of theinventionthe. deptheifectf-mthe final picture. is.

increased-by causing the picturemargin or frame to be stereoscopically moved forwardly or backwardly relative to themain body of the'picture itself. This may be accomplished in one method accordingto the invention bylemplo'yingfa margin frame element which is disposed betweenthe. lens and the lenticular, and by moving this ,-frame.'.

element during the taking of .the picture. Depending onthedirection of lateral movement of the frameelement with respect to'the lenticular. and the sensitized. surface, the finishedipictu're will be. provided with a-pictur margin or frame which will appear tobe either in front of or be hind the object .being photographed. The im vention also provides means for moving this..- frame element relatively to. other elements which mod-ify the. light passing. to the sensitized surface, i and for controlling the movement of such frame.

element.

. It is within the-contemplation: of the invention;

that the margin referred to above can be added, as-a printed border to any picture and does not necessarily have tobe-appliedv to the negative at.

the time the negative is lenticulatedstructurally, the invention provides 'a special camera back; which ;may: bedetachably; secured;. to :a; .standardstudio .camera. and .whichcamer-av; backa structure .ma-y be provided: with; a special...

filmfiholder; .aaholder for the :lenticular, a holder for the frame element, and means for effecting;

relative; movement ,between. such; elements 1: and

. for controlling the direction, of movement thereof the speed thereof, and-also forvaryingthe speed: of; movement'thereof' during; the taking; of. the. picture; It isa-n object'ofthe;inventiorrito pro.-.

vide such a structure.

; These. and other. objects :of; the-invention will,

become more apparent from the following description and claims when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagrammatic plan view of one arrangement in accordance with the invention;

Fig. 2 i a modified diagrammatic perspective View of the same;

Fig. 3 is a similar perspective of another arrangement;

Fig. 4 is a vertical longitudinal section taken through a special camera back and control unit constructed in accordance with the invention;

Fig. 5 is an enlarged detail of the mechanism for moving the margin frame;

Fig. 6 is front elevation taken on the line 6-6 of Fig. 4;

Fig. '7 is a rear elevation of the special camera back and control unit, the rear wall of the control unit having been removed;

Fig. 8 is an enlarged plan view of the control imit taken on the line 8--8 of Fig. 4;

Fig. 9 is an enlarged detail, in section, of one of the adjustable switch arms shown in Fig. 8;

Fig. 10 is an enlarged sectional view taken on the line l0-|0 of Fi '7;

Fig. 11 is a rear elevation of a modified form of control unit with the rear cover of the central portion thereof removed;

Fig. 12 is a top plan view of the same with the top removed;

Fig. 13 is a front elevation view of the same with the front wall removed, the figure also showing the upper portion of the mechanism for supporting the lenticular for movement;

Fig. 14 is a view taken on the line l4-I4 of Fig. 12, and being partially in section;

Fig. 15 is a top plan View of a preferred form. of control unit, with the top wall removed;

Fig. 16 is a rear elevation of the same with rear wall removed;

Fig. 17 is a front elevation of the same with the central portion of the front wall removed, and

Fig. 18 is a diagrammatic view of an electric circuit for said control unit and the elements controlled thereby.

While various forms of apparatus may be employed in carrying out the inventive concepts, the principal example of the invention here illustrated and described employs a stationary camera provided with a transparent lenticular screen between the lens and the film. The object to be photographed is preferably placed on a platform which is mounted for rotation around a center point which is disposed on or near the optical axis of the camera. Such an arrangement is shown very diagrammatically in Fig. 1 which is a plan view. Fig. 2 is a perspective view of the arrangement, which view is also very diagrammatic.

With reference now to these figures, the camera Ill having the usual bellows II, is provided at its rear with an open ended casing I 2 in which the film I3 is disposed. Disposed forwardly of,

lenticular l4 may be of any suitable transparent rigid material, but preferably is of a transparent plastic. The lenticular I4 is mounted in a holder l6 parallel to the film I3 and the holder IS, in turn, is mounted for a slight component of movement in its own plane in a direction at right angles to the length of said convex ribs, so that during the picture taking operation the lenticular [4 may be so moved in the direction of the arrow in Fig. 2.

Disposed within the camera l0 and forwardly of the lenticular I4, is a picture edging or margin frame I! which is disposed in a plane parallel to the film l3 and is mounted for movement in its own plane laterally in either direction. The purpose and operation of this frame ll will be described hereinafter.

The camera lens l8 preferably is a high quality process lens and is provided with a shutter and aperture arrangement of any type well known in the camera art.

The objects to be photographed are shown in Fig. 2 as comprising a pitcher and two cups and saucers which rest on a small table I9 which is placed on a platform 20. The platform 20 is provided with rollers 2| which are positioned so that the platform may be rotated about a vertical axis passing through the point P. The platform 20 may be rotated by various means, one of which is diagrammatically illustrated in Fig. l, as comprising an electric motor 22 connected to drive a gear 23 on an axle shaft 24 on which one of the rollers is secured. It will be noted from both Figs. 1 and 2 that the pivot point P is always positioned near or on the optical axis Y of the camera [0.

In Fig. 2 there is also shown a background screen 25 which is disposed on a wheeled support 26 so that the screen 25 may be moved laterally in the direction of the arrows.

It will thus be apparent that the type of apparatus illustrated here for the purpose of explaining one embodiment of the invention, comprises an arrangement in which, as the picture is being taken, the object is slowly rotated while at the same time the lenticular I4 is moved in its plane.

It should be apparent that such lateral movement of the lenticular has the effect of moving the image on the emulsion of the film as the picture is being taken and thus causes the effect of depth in the final picture.

Moreover, an increase in the depth effect is obtained by the lateral movement of the background screen 25 during the picture takin particularly if the rate of angular movement of this screen about the lens as an axis is greater than the rate of angular movement about said axis of any part of the object group.

The margin frame ll which also moves laterally, comprises in effect a sliding mask which produces the illusion, in the finished picture, of a margin to the rear or to the front of the plane of the main picture body, as desired. This frame is operated in synchronism with the lenticular [4 but in the opposite direction if it is desired to project the frame to the rear of the picture itself. To make the frame appear to be well out in front, the motion should be the same as that of the lenticular 14. Both efiects may be desired. For instance, a keyhole picture could be made with such a front framing in spite of the fact that the motion of the object and its lenticulation was such as to make it project forward, but not as much.

This mask or frame H is preferably placed just in front of the lenticular 14 in order to get the asse -110 effective would be a soft rounded or bent" edge of the frame being turned inward. This would probably reduce the blurring which results from lack of exact register between the lenticular and the picture where the latter is separately developed.

This lenticulated margin or frame can be printed in the negative at the time the lenticular itself operates on the picture image. However, a separate picture" of such a margin can be made and separately printed by press Work on the periphery of the positive or negative picture, complete with the runout on the inner edges bordering on the picture space, and then the picture itself can be printed over this, showing through the runout just as though the frame and the picture were taken and lenticulated together.

A third dimensional effect can be obtained with an arrangement employing a system in which, during the picture taking, there is relative lateral motion between the object and the lenticular. Broadly, the principal purpose of the present invention, as indicated, is to increase that depth effect greatly by introducing one or more additional relative lateral movements. These are produced by moving the lenticular edging frame I! and the background screen 25 in addition to rotating the object. Moreover, in some instances, as will be described, one or more of such movements may be accompaniedby movement of the camera it] and the lens 18 with respect to the object, and there may also for some cases be relative movement between the camera and its lens. In all events, the object is -to increase the depth effect in the final picture by such movement. It is, of course, apparent that each of these movements must be accurately prescribed and controlled.

It should be clear that in some instances it may be desirable to keep the object stationary and to swing the camera in an are about the center of the object. Such a system has been diagrammatically represented in Fig. 3 in which'elements similar to those in Figs. 1 and 2 have been given like reference numerals. Here also it is possible to effect a considerable number of relative movements between the various elements such as the film, the lenticular, the margin frame, the background frame, the lens, and the object. Here also it should be remembered that with regard to the margin frame it should be moved toward the right relative to the film l3 in the figure if, in the finished picture it is to appear to be behind the pivot point (the object), while if it is desired that it appear ahead of the pivot point it should be moved in the opposite direction but naturally at a different rate of speed than movement of the lenticular.

Referring again to the arrangement of Figs. 1 and 2 one practical mechanism for effecting the movements of the lenticular l4 and of the margin frame I! is illustrated in Figs. 4 to 10 inclusive. In this embodiment the camera It! which may be of a standard portrait studio type, is provided with the usual bellows l l and with a special, removable back structure which is enclosed within a main' casingfl'. The main casing 27 1s adapted' to'be removably secured to the rectangulan rearopen 1 end-of the camera I 3 by means of arectangular accommodation plate frame 28 which may be secured to the camera by means of screws 29' or the like. The accommodation plate frame-28, as shown, extends laterally outward-from the camera in all directions and the maincasing 21 is secured thereto by means of the screwsflfl', as is perhaps best shown in Fig. 4. Th'e m'ain casing 211s open at the rear, but the rear rectangular opening is adapted to be closed by a removable film holder 15, the special nature ofwhich will" be described shortly. The main casing has a shoulder 3| extending upwardly into therear opening and another shoulder 32 depending' downwardly. Thelenticular I4 and its holder l6 are positioned within the casing 21. The

lenticular I4 may be of the type heretofore men-' tioned which isprovidedwith vertical parallel convex ribs on its rear surface which ribs in 39 to fixed supports 40, 4| secured to, or forming.

an integral part of the main casing 21.

A support or'boss 42-rigid with the main cas-' ing 21 extends inwardly from the casing near theupper end thereof, and comprises a pivotal axis for a link'43. The link is pivotally connected as'at 44 to the lenticular holder IS. The link 43 has an upwardly extending dial indicator operating arm 45 and also an arm 46, both of which form rigid portions of the link 43. The arm 46 is provided with a threaded vertical hole 41 which receives the threaded end of an adjusting bolt 48. Abutting the upper end of the bolt 48 is-a-push rod 49 (Fig. 4) which extends upwardly through a hole 59 in the main casing 21 into a control'unit 51. As will be hereinafter described, the push rod 49'is actuated in an up and down movement by control mechanism in the control unit. The reference numeral 52 indicates a lug on the screen holder the purpose of which is to' guide the arm 46 in its movement. It will be noted that the position of the bolt 48 may be adjusted by means of the bolt head 53 and lock nut 54. A spring55 connected at one end to the lower end of the lenticular holder l6 and at the other to the main casing 21, constantly urges the bolt 48 into engagement with the push rod 49;

Because of the connections with the links 36, 31 and 43, movement of the push rod 49 in the manner indicated, will result in moving the lenticular holder I6, and the lenticular l4 carried thereby, in an arcuate path in its own plane. This arcuate path is indicated in Fig. 6 by the arrows 56. The lenticular holder I6 is sealed with respect to the main casing 2'1 by means of sealing strips 5'! (see Fig. 10 in particular).

Also mounted within the main casing 27 and forwardly of the lenticular holder I6 is the margin frame H, the purpose of which has been described above. This frame I! is comprised of a rectangular plate having a rectangular opening therein suitably dimensioned to accomplish its stated purpose. The frame I! is mounted to the main casing by double pivot hinges 58 in such manner that'the frame may be moved in its own plane laterally in either direction depending upon the effect-which it is desired to create in the fin-.

ished picture. This movement is effected through the means of a pin 59 which extendsforwardly from the link 36. The pin has a roller 60 thereon which engages an adjustable cam BI carried by the frame I! (see Figs. 4 and 5). The cam 6| is such that the arcuate movement of the pin 59 with the link 36 is translated into a straight horizontal movement of the frame It is advisable to make the cam 6| adjustable so that the cam surface can be disposed either in positions resulting in lateral movement in either direction, or in various intermediate positions which would efiect but minor lateral movement. Also preferably, the cam should be capable of adjustment to a position in which no lateral movement of the frame at all will be efiected. Other suitable mechanism for moving the frame laterally can of course be used.

Reference'is now made to the film holder |5 and'the manner in which it may be positioned and removed from the rear open end of the main casing 21. The film holder |5 which comprises the back cover for the main casing 21 when it is in closed position, may be a rectangular fiat plate provided around its periphery with a forwardly directed flange 62 which is adapted to be engaged in the rear opening of the casing in a space formed by the edge of the opening and the rearwardly stepped portion of the lenticular holder I8 (Fig. 10) A sealing strip 63 of rubber or the like provides an air-tight, and light-tight joint between the flange 62 of the film holder I5, the main casing 21 and the lenticular holder H5.

The arrangement is such that when the film holder I5 is in the position in which it closes the opening in the rear of the main casing, the film l3 will be slightly spaced from the lenticular It. It will be noted from Fig. 10 that there is an air space 64 between the film l3 and the lenticular M, as this is the preferable construction. The shoulder 3| on the main casing 21 is provided with an air passage 65 which extends to the air space. The film holder |5 is also provided with a passage 66 which leads from a vacuum source (not shown) to the back of the film. The vacuum thus maintains the film l3 tightly against the film holder I5. Air supplied through the air passage to the space between the lenticular l4 and the film l3 also aids in'so maintaining the film against its holder and also in insuring that there be a proper space between the film and the lenticular.

The film could contact the face of the lenticular, but where the lenticular is plastic or the like relative movement between the two may cause the lenticular to become scratched.

The film holder i5 is inserted in place in the position indicated in Figs. 4 and '7 by holding it in a vertical plane and moving it bodily forward until the flange 62 is engaged as shown in Fig. 10. So that the film holder may be accurately positioned within the rear opening of the main casing 21, the casing (as shown in Fig. 7) is provided with a number of position adjusting screws 61, 68, and 69, the inner ends of which protrude inwardly into the rear opening along one side and the bottom thereof. These screws are threaded in the casing and can'be secured in any adjusted position by means of the lock nuts provided for that purpose.

Means are provided for securing the film holder IS in operative position and for quickly removing it, together with the film, after the picture has been taken and the film is ready for develop ment. Such means is comprised of a plurality of quick-acting pivoted clamps I0 which are pivoted to the main casing 21 for swinging movement into and out of clamping position. In Fig. l, one of the clamps 10 is shown in the upper part of the drawing figure in closed position in wall of the cylinder tion on the rear of the main casing, it is only main frame (as at H in Fig. 4).

' bolts 79.

full lines and in partially open position in dotted lines. Each of these clamps is the same structurally and is comprised of a G-shaped portion one end of which is pivotally connected to the The other end of each of the clamps 10 is provided with a hole which communicates with a cylinder H. The stem 12 of a T-shaped operating handle 13 passes through the cylinder H and through the end of the C-shaped portion and this stem is urged inwardly by means of the coil spring 14 which is disposed within the cylinder H and which at one end bears against a collar 14 rigid with the stem 12 and at the other end against the end The reference numerals l5, 16, H, and 18 (Fig. '7), indicate four lugs which extend laterally from the four corners of the film holder Hi. In each of these there is threadedly mounted an adjusting stop bolt 19 which extends rearwardly and the position of which, after adjustment, can be set by means of the lock nuts 80. It will be noted, particularly from Fig. 4, that it is these stop bolts H! which are adapted to be engaged 'by the spring pressed stems 12 of the handles 73 of the clamps it when the latter are in clamping position.

It should now be appreciated that when it is desired to lock the film holder in operative posinecessary to swing the clamps into place, pulling out the handles 13 of the clamps l0 until the clamps are in a position in which the stems 12 of the clamps are in alignment with the stop The handles are then released so that the stems engage and press against the stop bolts thus securing the film holder rigidly in closed position. Moreover, it should now be evident that to remove the film holder after a picture has been taken, it is merely necessary, if the camera is in a dark room, to pull out the handles of each of the clamps, swing the clamps to unlocked position, and then bodily remove the film holder. Removal of the film holder in this fashion is facilitated by grasping the lugs l5, 76, Ti and 18 which extend laterally from the film holder at its four corners as previously described. If it is desired to be able to remove the back when the camera is not in a dark room, the film holder should be provided with a slit (not shown) through which a dark slide can be inserted to protect the film from light before the film holder is removed.

Reference is now made to the control unit 5| which, as will be noted from Figs. 4 and 6 of the drawings, is removably secured to the upper part of the main casing 21 by means of screws or bolts 8|. Within the lower part of the control unit 5| is a support member 82 (Fig. 4) which is provided with a vertical bore for the push rod 49 which extends upwardly therethrough. Depending from the top of the control unit 5| is a bracket support 83 for a gear assembly. Mounted in bearings in the bracket support 83 is a shaft 84 on which is rigidly mounted a gear 85. This shaft M extends rearwardly through the casing of the control unit 5| and the end thereof is provided with an operating handle or crank 86. The other end of the shaft 84 Within the casing of the control unit .ed to engage the cam surface of the cam-93. arrangement is such that asthe cam 93 rotates lenticular holder I6.

.support I99 by any suitable means'such as by .the bolts H6, III.

5| is provided with a rigid bevel gear 86 which is engaged by a bevel gear .81 on the end of a vertical shaft 88 which extends upwardly through the top of the casingof the control unit where it is connected by suitable gearing through a slip clutch (not shown) to be driven by the electric motor 89.

The gear 85 engages another gear 99 which is mounted on a shaft9I supported for rotation in bearings in the bracket support 83. Mounted 10 on the shaft 9I so .as to rotate therewith is a cam 92 (Fig. 4) for controlling the movement of the lenticular holder I6, in a manner'which will be described shortly. Also mounted on the shaft 9| so as to rotate therewithis another cam 93 the cam surface of which controls the actuation of limit switches 94 and 95 (Figs. 6. and '7) the purpose of which will be shortly described.

The cam 92 is adapted to be engaged by a roller 96 (Fig. 4) which is mounted in a bifurcated yoke 96' disposed on the upper end of the push rod 49, said push rod 49 being spring pressed in .an upward direction into engagement with the surface of the cam 92 by the spring 55 (Fig. 6).

It will now be noted that operation of the motor 89 will revolve shaft 88 and through bevel gears 81 and 86 will rotate the shaft and the gear Rotationof the gear 85 causes rotation of the gear 90 and of the shaft9I and of the two earns 92 and 93 mounted thereon. As the cam 92 is rotated, the push rod 49 will follow the cam surface and will be moved in an upward or downward direction as the case may be. Consequently, this movement of the push rod moves the arm 46 of .the link 43 (Fig. 6) .and through the mechanism described effects movement of the lenticular hold- ,er I6 in an arcuate path as indicated by the arrows 56 in Fig. 6.

Asshown in Fig. 4, the cam 92, 93- can be set in any desired position by means of turning the turns the shaft 9|. Such setting movement is permitted by the slip clutch in thegear housing adjacent the motor 89.

Mounted on supports 91 within the controlunit .5I, by means of the screws 98, is a timing circle 99. Mounted on a stub shaft I supported by .the boss iilI (Figs. 7 and 8) are two arms I02 .and I03, each of which carries one of the shutter timing switches 94, 95.

It will be noted-that the position of the arms I02 and I03 may be adjusted with respect to the circle 99. In any-adjusted position these arms I02 and I03 may be secured to the circle 99 by means of the shutter timing position clamp screws I04. Each of the timing switches carries a spring pressed plunger contact I05 and I96 respectively, both of which are adapt- The first one and then the other of the switches 94 and 95 will be actuated. These switches are connected in a circuit which includes a solenoid until the cam actuates the second switch whereupon the shutter is closed. Adjustment of the arms I62 and I03 controls the position of the "switches 94, 95, and consequently controls the time during which the shutter will be open for the taking of a picture.

The two switches I01, I98 (Fig. '7) are limit switches for controlling the movement of the They are mounted on the These switches I91, I08 each have-a springpressed plunger H2 and H3, re-

spectively, which engage the cam surface of the cam 93. The actuation of the first switch I01 as the cam revolves, starts the electric motor 89 and through the mechanism described actuates the lenticular holder I6 through its arcuate path.

This movement occurs during time that the shutter is open. The actuation of the second switch I08 shuts off the electric motor andstops the movement of the lenticular holder I6.

It will be noted, moreover, that as the lenticular holder I6 is moved, the margin frame I1 is also moved in-a horizontal direction as has been previously described The movement of the lenticular holder I6, of the frame IT, and the opening and closing of the shutter of the camera, can all be made to synchronize with rotary'movement of the platform (Figs. 1 and 2) on which the objects being 20 photographed have been placed. This can allbe effected through a circuit which may be connected with the switches described through the socket or receptacle I I4 shown in Fig. 6.

It is of course desirable to have an indicator on the control unit 5I so that the operatorcan observe the amount of movement of the lenticular holder I6. Such an indicator has been illustrated in the drawings (Figs. Sand 7) where it is designated by the reference numeral II5. This may be a simple dial indicator, properly graduated, and provided with an indicating hand mounted-to rotate about the dial. The movement of the hand may be controlled by a springpressed plunger II6 which engages the dial indicator operating arm .45. Consequently, as the indicate the extent of movement of the lenticular crank 86 which actuates the gears 85, 90 and" .holder.

Another control unit is illustrated in Figs. 11, -12, 13 and 14. This control unit which is generally indicated by the reference numeral I I1, is so constructed that the arm H8 (which is the equivalent of arm 45) and which forms a part of the link 43 of the mechanism for moving the lenticular holder I6, carries a rack II9 which is engaged by a rotating pinion I20 (Fig. 13). Consequently, the lenticular holder I6 is actuated through this rack and pinion arrangement.

Mounted within the casing of the control unit II'I (Fig. 12) is a dial indicator I2I, the dial I22 of which is adapted to be actuated through a spring pressed plunger I23 which engages an indieating plate I24 carried by the arm I [8. It will be noted that movement of the arm IIB causes the dial to-move on the indicator and that this indicator can thus indicate at all times the movement of the lenticular I4.

0n the otherside of the control unit II! is a .shuttertime indicator I25 which may be driven by a small electric timing-motor I26. The dial of this indicator is suitably marked (Fig. 11) 'so that the indicator hand will indicate the time in seconds that the shutter is open during the taklar holder I6 .will-now be described. In Fig. 12

the reference number I23 indicates a small electric motor, the drive shaft I29 of which is connected by a coupling element I39 to a shaft I3I.

The shaft I3I extends through the partition I21 and on its end is rigidly mounted a small pinion gear I32. This gear I32 engages a large gear I33 which is mounted on a shaft I34 mounted in hearings in the bearing box I35 secured to the partition I21. Mounted on the same shaft I34 is. another large gear I36 and also a detent disc I31. .The shaft I34 extends through the partition I2'I. towards the motor side of the control unit and on its end is rigidly mounted the pinion I26 which engages the rack as previously described.

The arrangement is such that the small gear I32 on shaft I3I drives the large gear I33 thus turning the shaft I34, such rotary movement of the shaft I34 causing rotation of the pinion I29 and actuation of the rack II9 thus moving the lenticular holder I3 in the manner which has been described hereinbefore.

The gears I32 and I33 are readily removable and may be replaced with gears of various sizes so as to change the rate of movement.

tition I21 and on its end has a cam I4I thereon which rotates with the shaft. Carried by the partition I21 are two limit switches I42 and I43, each provided with a spring pressed contact I44 and I45 respectively. These contacts I44 and I45 are disposed in the path of the cam I4I as it rotates. They are electrically connected in the circuit, for the electric motor I28 so as to start and stop the motor and thus control the duration of movement of the lenticular holder I6.

The shaft I49 on its other end carries another cam I 46. Disposed below this cam I46 and secured to the bearing box I35 is another switch I41 having a spring pressed contact I48 adapted to engage the cam I46 during its rotation. This cam is so designed as to control the time during which the camera shutter is open during the taking of the picture. The cams MI and I45 are adapted to be replaced by other similar cams (not shown) which are provided with various cam surfaces providing for different operating times or these cams may be of an adjustable type. During normal motor driven operation the spring pressed ball I38 is removed so that the detent disc can rotate freely with the gearing.

The purpose of the detent disc I31 and spring pressed ball I38 is to permit the apparatus to be used for taking a succession of shots, one at a time. In such instances the gears are moved by hand (or they may be jogged by momentary contact of the motor switch), and the detent permits accurate step by step positioning of the lenticular in a lateral direction.

As previously indicated, it is desirable in some cases to provide means whereby the rate of motion of the lenticular holder I6 may be varied. For example, it has been found to be very advantageous in some cases to control the rate of motion of the lenticular I4 so that its motion is first fast, then slow, and finally fast again. The slower rate in this case would be through the middle part of the cycle in order to bunch the picture so as to allow the eyes to subtend an increased portion of the total see around motion included in the total .lenticular width. It will be noted that this will be of increasing importance as the viewing is done from distances greater than arms length.

With bunched exposures, the middle part of the lenticular would be overexposed. It is proposed to vary the f/no. of the lens by stopping it down during this period of the cycle and thus gain the double benefit of reducing the width of the single image line made by. the lens. With a narrower line the middle region of thelenticular can accommodatemore lines per unit width with the same degree of overlap normally experienced. 1

In accordance with the invention, therefore, it is the object of the mechanism to be described to accelerate the motion imparted to the lenticular at the beginning and end of its travel and to slow it down distinctly during the middle of its stroke. Moreover, it has been found desirable at this stage simultaneously to reduce the aperture at the lens in order to keep substantially the same density in the resulting exposure. In fact, in actual practice, the exposure of the central portion of the negative may be made more dense so as to obtain slightly less density in the central portion of the positive so as to brighten up the central portion of the. positive. This results in attracting more attention to this portion of the picture when viewed.

One means for accomplishing the variable motion of the lenticular I4 and of the aperture opening for the lens of the camera, is illustrated in Figs. 15, 16, and 17. These figures disclose a control unit I49, which, similarly to those heretofore described is adapted to be removably secured to the upper portion of the casing of the camera II] as shown in Fig. 4.

The control unit I49 of Figs. 15, 16, and 17, is enclosed in a casing I59 which is divided intermediate its front and back by a partition I5I. The front of the casing I50 is provided with a removable cover I52 which supports the electric motor I53, the drive shaft I54 of which (when the cover is in place) extends within the casing I50 and is adapted to connect with a coupling member I55. The coupling member I55 joins the shaft I54 of the motor with a shaft I 56 which is supported by bearings mounted in the partition I5I. The shaft I56 extends rearwardly of the partition and has a gear I 51 mounted thereon to rotate therewith.

The gear I51 engages a gear I58 mounted on a shaft I59 which is supported by the partition I5I. Mounted on the shaft I59, also, is a detent disc I60, the periphery of which is notched, and the notches being engaged by a spring pressed pivoted pawl I6I. This pawl is constructed like a snap switch to snap to either side of a clutch position, and is shown in one of these positions. The shaft I59 extends forwardly through the partition and has a gear I62 mounted thereon near its end. The gear I62 will be referred to hereinafter as the fast gear. It is provided with gear teeth around substantially all of its periphery and may be secured to the shaft I59 by means of the set screw I63 located on the portion not having teeth. 

